linux-kernel - [PATCH v3 0/2] Fix RISC-V's arch-topology reporting

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Message-Id: <20220709152354.2856586-1-mail@conchuod.ie>
Date:   Sat,  9 Jul 2022 16:23:53 +0100
From:   Conor Dooley <mail@...chuod.ie>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Sudeep Holla <sudeep.holla@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Daire McNamara <daire.mcnamara@...rochip.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Niklas Cassel <niklas.cassel@....com>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Zong Li <zong.li@...ive.com>,
        Emil Renner Berthing <kernel@...il.dk>,
        Jonas Hahnfeld <hahnjo@...njo.de>, Guo Ren <guoren@...nel.org>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Philipp Tomsich <philipp.tomsich@...ll.eu>,
        Rob Herring <robh@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Brice Goglin <Brice.Goglin@...ia.fr>
Subject: [PATCH v3 0/2] Fix RISC-V's arch-topology reporting

From: Conor Dooley <conor.dooley@...rochip.com>

Hey all,
It's my first time messing around with arch/ code at all, let alone
more than one arch, so forgive me if I have screwed up how to do a
migration like this.

The goal here is the fix the incorrectly reported arch topology on
RISC-V which seems to have been broken since it was added.
cpu, package and thread IDs are all currently reported as -1, so tools
like lstopo think systems have multiple threads on the same core when
this is not true:
https://github.com/open-mpi/hwloc/issues/536

arm64's topology code basically applies to RISC-V too, so it has been
made generic along with the removal of MPIDR related code, which
appears to be redudant code since '3102bc0e6ac7 ("arm64: topology: Stop
using MPIDR for topology information")' replaced the code that actually
interacted with MPIDR with default values.

I only built tested for arm{,64} , so hopefully it is not broken when
used. Testing on both arm64 & !SMP RISC-V would really be appreciated!

For V2, I dropped the idea of doing a RISC-V specific implementation
followed by a move to the generic code & just went for the more straight
forward method of moving to the shared version first. I also dropped the
RFC.

V3 moves store_cpu_topology() down inside the arch check alongside the
init function so that boot on 32bit arm is not broken.

Thanks,
Conor

Conor Dooley (2):
  arm64: topology: move store_cpu_topology() to shared code
  riscv: topology: fix default topology reporting

 arch/arm64/kernel/topology.c | 40 ------------------------------------
 arch/riscv/Kconfig           |  2 +-
 arch/riscv/kernel/smpboot.c  |  4 +++-
 drivers/base/arch_topology.c | 19 +++++++++++++++++
 4 files changed, 23 insertions(+), 42 deletions(-)

base-commit: b6f1f2fa2bddd69ff46a190b8120bd440fd50563
-- 
2.37.0